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Many properties are based on the interaction of light with matter and they open the door to many practical applications. For example, sunlight is a gigantic environmentally friendly energy source and the project developed in IMF group in the area of dye sensitized solar cells and artificial photosynthesis aim at exploiting this fantastic energy resource.

Upon light absorption, the energy stored by matter can be subsequently used to either promote a catalytic process with metal nanoparticles or clean up water without the need to use detergents, which constitutes another research activity in IMF.

Beyond the energy content of the photon, light can be view as an energy bit that is used by the team to write on matter in order to store massive amount of information.

PI: Fabrice ODOBEL

As compared to the much extensively developed silicon based solar cells, dye sensitized solar cells (DSSCs) present the discriminating advantages of having a shorter energy payback time, the color of the cell is tunable over all the rainbow, they are transparent and aesthetic, compatible with flexible substrates, they are lightweight and very importantly they display higher performances under low light conditions and particularly under artificial lightning. For example, Hagfeldt and co-workers report an efficiency up to 28.9% under indoor illumination with a model Osram 930 warm-white fluorescent light tube (1000 lux), which even outperforms a GaAs thin-film solar cell in the same conditions.1

Accordingly, DSSCs represent an attractive solution to produce electricity with low cost and is a valuable technology for building integrated photovoltaic (BIPV) or for indoor applications. The works on DSSCs is also driven by the possible implementation of these photoelectrodes to design dye sensitized photoelectrosynthetic cells (DSPECs) for solar fuels, another area of our interest (see artificial photosynthesis projects).  Basically, our works on DSSCs focus on two main directions:

1. Convention n-type dye sensitized solar cells (n-DSSCs) based on TiO2

There are two different research domains in the area of DSSCs. In the first one, the cells are based on the sensitization of an n-type semi-conductor (essentially TiO2) and are better known as “Grätzel cells” and there have been many extensive studies on this field. Recently, our interest was directed towards two main topics: i) amplification of the light collection by antenna effect and ii) the development of organic dyes for colorless and transparent solar cells.

1.1 Light collection by antenna applied to DSSCs

In plants and photosynthetic organisms sunlight is collected by a large number of chromophores called Light Harvesting Antenna (LHA) embedded around the Photosynthetic Reaction Center. The LHA enables to achieve a large absorption cross section thanks to the numerous molecular absorbers, composed of chlorophyll derivatives and carotenoids, having complementary absorption spectra. The fantastic property of the LHA ensures that each photon absorbed by any chromophore in the LHA is funneled to the Photosynthetic Reaction Center with a quantum efficiency close to unity.

IMF schematic illustration of antenna effect in a DSSC and molecur system used

The first step of any photovoltaic process is to collect photons, accordingly it appears logical to get inspiration from the strategy developed by Nature over billion year of evolution to optimize this function. In other words, we have prepared multi-chromophoric array to maximize the absorption cross-section of a DSSC (Figure 1).

The role of the antennas is to collect photons where the sensitizer is a poor absorber and to transfer the energy to the sensitizer (Figure 1).3 Towards this objective, we have appended supplementary chromophores playing the role of antennas such as a boroazaindacene (Bodipy), a zinc porphyrin (ZnP) or a diketopyrrolopyrrole (DPP) linked to a squaraine (SQ) sensitizer (Figure 1). The supplementary chromophores (antennas) can be connected to the sensitizer either by covalent bond4, 5 or by supramolecular interaction.6, 7

1.2 Colorless and transparent DSSCs

Visibly transparent solar cells is an emerging concept, which has garnered increasing recent scientific attention. It can afford significant energy production by providing electricity via transparent and colorless windows in buildings and cars. Moreover, colorless sensitizers can constitute valuable complementary dyes to fabricate panchromatic DSSC, which would exploit sunlight from ultraviolet (UV) to the near infrared (NIR).

Towards this application, we have designed and prepared original dyes presenting high transmission in the visible region (400-700 nm), but high absorbance in the UV and more particularly in the NIR (> 700 nm), where the flux of photons is significant. Several families of dyes are currently explored toward this end; among them original dyes (patent registration under way), but also phthalocyanines (SiPc)8, 9 and diazabenzoporphyrines (CROSSDAP)10 derivatives whose extended absorption bands situated in the NIR are particularly appealing (Figure 2).

Structure of a diazabenzoporphyrin (CROSSDAP) and a phthalocyanine (SiPc) NIR sensitizers

Structure of a diazabenzoporphyrin (CROSSDAP) and a phthalocyanine (SiPc) NIR sensitizers

2. Inverted p-type dye sensitized solar cells (p-DSSCs) based on the sensitization of a wide bandgap semiconductor such as NiO

Apart from classical n-DSSCs, there is a second category of DSSCs, much less documented, based on the sensitization of a p type wide bandgap inorganic semi-conductor (usually NiO). The operation principle of a pDSSC is based on the photo-injection of a hole from the sensitizer into the valence band of the p-SC (mainly NiO).11, 12, 13 We have importantly contributed to this much less investigated research field, by developing organic and quantum dot photosensitizers, analyzing their physical properties by absorption and emission spectroscopies and electrochemistry, and finally building and evaluating our own photovoltaic devices.

This was possible, thanks to the precious time-resolved photophysical studies thanks to a long time collaboration with Pr. Leif Hammarström (Uppsala Sweden) and more recent one with Prof. Eric Vauthey (Geneva University). More precisely, we have explored various classes of organic dyes (Figure 3) such as perylene imides (PI),14, 15 porphyrines,16, 17 diketopyrrolopyrroles (DPP),18, 19 push-pull dyes20, 21 and inorganic systems such as PbS quantum dots22, 23 (Figure 4) and iridium24, 25 and ruthenium25, 26 polypyridine complexes (Figure 3) as NiO sensitizers.

Structures of some dyes prepared and studied in p-DSSCs

Figure 3 : Structures of some dyes prepared and studied in p-DSSCs

Schematic representation of the QD based p-QDSSC (left) and photo-action spectrum (red) along with current/voltage characteristics (black) of a PbS based p-QDSSC (right).

Figure 4 : Schematic representation of the QD based p-QDSSC (left) and photo-action spectrum (red) along with current/voltage characteristics (black) of a PbS based p-QDSSC (right).

NiO is the most investigated p-SC in p-DSSCs, but it presents many drawbacks,13 which prompted the scientific community to explore alternative oxides with p-type semi-conductivity. In this context, in collaboration with Prof. Stéphane Jobic at IMN (Institut des Matériaux Jean Rouxel) we have shown that delafossites such as CuGaO2 are other copper based oxides are promising substitutes of NiO, because they are less colored materials and their valence band is deeper giving thus a higher photovoltage.27, 28, 29, 30, 31

Finally, the photocathodes made of p-type sensitized SCs provide the entry into the field of tandem dye sensitized solar cell (t-DSSC), since the latter can be connected to a TiO2 photoanode to build a two absorbers solar cell, whose performances could be greater than those of single absorber DSSC. In this area, we have prepared the most efficient tandem DSSC reported so far and whose efficiency is higher than that of the individual sub-cell (Figure 5).32

IMF - tandem DSSC

Figure 5 : (a) Schematic illustration of a tandem DSSC with the structures of the sensitizers on each on NiO and TiO2 ; (b) electrodes current/voltage curves of the sub-cells (NiO and TiO2 based DSSC) and of the tandem and (c) table gathering the characteristics of the cells.

 

Collaborations :

 

Financements :

  • Project POSITIF (ANR Progelec, 2012-2017) ;
  • Project QuePhelec (ANR blanc, 2013-2017) ;
  • Project Vision-NIR (ANR, 2018-2022), LUMOMAT (Région Pays de la Loire).

 

Références :

  1. M. Freitag; J. Teuscher; Y. Saygili; X. Zhang; F. Giordano; P. Liska; J. Hua; S. M. Zakeeruddin; J.-E. Moser; M. Grätzel; A. Hagfeldt, "Dye-sensitized solar cells for efficient power generation under ambient lighting." Nature Photonics, 2017, 11, 372, http://dx.doi.org/10.1038/nphoton.2017.60.
  2. G. McDermott; S. M. Prince; A. A. Freer; A. M. Hawthornthwaite-Lawless; M. Z. Papiz; R. J. Cogdell; N. W. Isaacs, "Crystal structure of an integral membrane light-harvesting complex from photosynthetic bacteria." Nature, 1995, 374, 6522, 517-521, http://dx.doi.org/10.1038/374517a0
  3. F. Odobel; Y. Pellegrin; J. Warnan, "Bio-inspired artificial light-harvesting antennas to enhance solar energy capture in dye-sensitized solar cells." Energy Environ. Sci., 2013, 6, 7, 2041-2052, http://dx.doi.org/10.1039/C3EE24229C.
  4. J. Warnan; L. Favereau; F. Meslin; M. Severac; E. Blart; Y. Pellegrin; D. Jacquemin; F. Odobel, "Diketopyrrolopyrrole–Porphyrin Conjugates as Broadly Absorbing Sensitizers for Dye-Sensitized Solar Cells." ChemSusChem, 2012, 5, 8, 1568-1577, http://dx.doi.org/10.1002/cssc.201100764.
  5. J. Warnan; F. Buchet; Y. Pellegrin; E. Blart; F. Odobel, "Panchromatic Trichromophoric Sensitizer for Dye-Sensitized Solar Cells Using Antenna Effect." Org. Lett., 2011, 13, 15, 3944-3947, http://pubs.acs.org/doi/abs/10.1021/ol2014686
  6. J. Warnan; Y. Pellegrin; E. Blart; F. Odobel, "Supramolecular light harvesting antenna to enhance absorption cross-section in dye-sensitized solar cells." Chem. Commun., 2012, 48, 5, 675-677, https://pubs.rsc.org/en/content/articlelanding/2012/cc/c1cc16066d#!divAbstract.
  7. G. Charalambidis; K. Karikis; E. Georgilis; B. L. M'Sabah; Y. Pellegrin; A. Planchat; B. Lucas; A. Mitraki; J. Boucle; F. Odobel; A. G. Coutsolelos, "Supramolecular architectures featuring the antenna effect in solid state DSSCs." Sustainable Energy & Fuels, 2017, 1, 2, 387-395, http://dx.doi.org/10.1039/C6SE00051G.
  8. J. Fortage; E. Göransson; E. Blart; H.-C. Becker; L. Hammarström; F. Odobel, "Strongly coupled zinc phthalocyanine-tin porphyrin dyad performing ultra-fast single step charge separation over a 34 Ã distance." Chem. Commun. 2007, 44, 4629-4631, https://pubs.rsc.org/en/content/articlelanding/2007/CC/b711642j#!divAbstract.
  9. F. Odobel; H. Zabri, "Preparations and Characterizations of Bichromophoric Systems Composed of a Ruthenium Polypyridine Complex Connected to a Difluoroborazaindacene or a Zinc Phthalocyanine Chromophore." Inorg. Chem., 2005, 44, 16, 5600-5611, https://pubs.acs.org/doi/abs/10.1021/ic050078m.
  10. D. S. Andrianov; Y. Farre; K. J. Chen; J. Warnan; A. Planchat; D. Jacquemin; A. V. Cheprakov; F. Odobel, "Trans-disubstituted benzodiazaporphyrin: A promising hybrid dye between porphyrin and phthalocyanine for application in dye-sensitized solar cells." J. Photochem. Photobiol., A, 2016, 330, 186-194, https://www.sciencedirect.com/science/article/pii/S1010603016303215.
  11. F. Odobel; L. Le Pleux; Y. Pellegrin; E. Blart, "New photovoltaic devices based on the sensitization of p-type semiconductors: challenges and opportunities." Acc. Chem. Res., 2010, 43, 8, 1063-1071, https://pubs.acs.org/doi/10.1021/ar900275b.
  12. F. Odobel; Y. Pellegrin; E. A. Gibson; A. Hagfeldt; A. L. Smeigh; L. Hammarström, "Recent advances and future directions to optimize the performances of p-type dye-sensitized solar cells." Coord. Chem. Rev., 2012, 256, 21–22, 2414-2423, http://www.sciencedirect.com/science/article/pii/S0010854512000999?v=s5.
  13. F. Odobel; Y. Pellegrin, "Recent advances in the sensitization of wide-band-gap nanostructured p-type semiconductors. Photovoltaic and photocatalytic applications." J. Phys. Chem. Lett., 2013, 4, 15, 2551-2564, http://dx.doi.org/10.1039/C1EE01148K.
  14. E. A. Gibson; A. L. Smeigh; L. L. Pleux; J. Fortage; G. Boschloo; E. Blart; Y. Pellegrin; F. Odobel; A. Hagfeldt; L. Hammarström, "A p-Type NiO-based Dye-Sensitized Solar Cell with a Voc of 0.35 V." Angew. Chem. Int. Ed., 2009, 48, 24, 4402-4405, https://pubs.acs.org/doi/abs/10.1021/jz400861v.
  15. L. Le Pleux; A. L. Smeigh; E. Gibson; Y. Pellegrin; E. Blart; G. Boschloo; A. Hagfeldt; L. Hammarström; F. Odobel, "Synthesis, photophysical and photovoltaic investigations of acceptor-functionalized perylene monoimide dyes for nickel oxide p-type dye-sensitized solar cells." Energy Environ. Sci., 2011, 4, 6, 2075-2084, https://pubs.rsc.org/en/content/articlelanding/2011/ee/c1ee01148k#!divAbstract.
  16. A. Maufroy; L. Favereau; F. B. Anne; Y. Pellegrin; E. Blart; M. Hissler; D. Jacquemin; F. Odobel, "Synthesis and properties of push-pull porphyrins as sensitizers for NiO based dye-sensitized solar cells." J. Mater. Chem. A, 2015, 3, 7, 3908-3917, http://dx.doi.org/10.1039/C4TA05974C.
  17. L. Zhang; L. Favereau; Y. Farre; A. Maufroy; Y. Pellegrin; E. Blart; M. Hissler; D. Jacquemin; F. Odobel; L. Hammarstrom, "Molecular-structure control of electron transfer dynamics of push-pull porphyrins as sensitizers for NiO based dye sensitized solar cells." RSC Adv., 2016, 6, 81, 77184-77194, http://dx.doi.org/10.1039/C6RA15195G.
  18. L. Favereau; J. Warnan; Y. Pellegrin; E. Blart; M. Boujtita; D. Jacquemin; F. Odobel, "Diketopyrrolopyrrole derivatives for efficient NiO-based dye-sensitized solar cells." Chem. Commun., 2013, 49, 73, 8018-8020, https://pubs.rsc.org/en/content/articlelanding/2013/cc/c3cc44232b#!divAbstract.
  19. Y. Farré; L. Zhang; Y. Pellegrin; A. Planchat; E. Blart; M. Boujtita; L. Hammarström; D. Jacquemin; F. Odobel, "Second Generation of Diketopyrrolopyrrole Dyes for NiO-Based Dye-Sensitized Solar Cells." J. Phys. Chem. C, 2016, 120, 15, 7923-7940, http://dx.doi.org/10.1021/acs.jpcc.5b12489.
  20. Y. Farré; M. Raissi; A. Fihey; Y. Pellegrin; E. Blart; D. Jacquemin; F. Odobel, "Synthesis and properties of new benzothiadiazole-based push-pull dyes for p-type dye sensitized solar cells." Dyes Pigments, 2018, 148, Supplement C, 154-166, http://www.sciencedirect.com/science/article/pii/S0143720817314481.
  21. P. Naik; A. Planchat; Y. Pellegrin; F. Odobel; A. Vasudeva Adhikari, "Exploring the application of new carbazole based dyes as effective p-type photosensitizers in dye-sensitized solar cells." Solar Energy, 2017, 157, 1064-1073, http://www.sciencedirect.com/science/article/pii/S0038092X1730796X.
  22. M. Raissi; Y. Pellegrin; S. Jobic; M. Boujtita; F. Odobel, "Infra-red photoresponse of mesoscopic NiO-based solar cells sensitized with PbS quantum dot." Sci. Rep., 2016, 6, doi: 10.1038/srep24908, http://dx.doi.org/10.1038/srep24908.
  23. M. Raissi; M. T. Sajjad; Y. Pellegrin; T. J. Roland; S. Jobic; M. Boujtita; A. Ruseckas; I. D. W. Samuel; F. Odobel, "Size dependence of efficiency of PbS quantum dots in NiO-based dye sensitised solar cells and mechanistic charge transfer investigation." Nanoscale, 2017, 9, 40, 15566-15575, http://dx.doi.org/10.1039/C7NR03698A.
  24. M. Gennari; F. Légalité; L. Zhang; Y. Pellegrin; E. Blart; J. Fortage; A. M. Brown; A. Deronzier; M.-N. Collomb; M. Boujtita; D. Jacquemin; L. Hammarström; F. Odobel, "Long-Lived Charge Separated State in NiO-Based p-Type Dye-Sensitized Solar Cells with Simple Cyclometalated Iridium Complexes." J. Phys. Chem. Lett., 2014, 5, 13, 2254-2258, http://pubs.acs.org/doi/abs/10.1021/jz5009714.
  25. F. Légalité; D. Escudero; Y. Pellegrin; E. Blart; D. Jacquemin; O. Fabrice, "“Iridium effect” in cyclometalated iridium complexes for p-type dye sensitized solar cells." Dyes Pigments, 2019, 171, 107693, http://www.sciencedirect.com/science/article/pii/S0143720819301871.
  26. Y. Pellegrin; L. Le Pleux; E. Blart; A. Renaud; B. Chavillon; N. Szuwarski; M. Boujtita; L. Cario; S. Jobic; D. Jacquemin; F. Odobel, "Ruthenium polypyridine complexes as sensitizers in NiO based p-type dye-sensitized solar cells: Effects of the anchoring groups." J. Photochem. Photobiol., A, 2011, 219, 2-3, 235-242, https://www.sciencedirect.com/science/article/pii/S1010603011000876.
  27. A. Renaud; B. Chavillon; L. Le Pleux; Y. Pellegrin; E. Blart; M. Boujtita; T. Pauporte; L. Cario; S. Jobic; F. Odobel, "CuGaO2: a promising alternative for NiO in p-type dye solar cells." J. Mater. Chem., 2012, 22, 29, 14353-14356, https://pubs.rsc.org/en/content/articlelanding/2012/JM/c2jm31908j#!divAbstract.
  28. A. Renaud; L. Cario; P. Deniard; E. Gautron; X. Rocquefelte; Y. Pellegrin; E. Blart; F. Odobel; S. Jobic, "Impact of Mg Doping on Performances of CuGaO2 Based p-Type Dye-Sensitized Solar Cells." J. Phys. Chem. C, 2014, 118, 1, 54-59, http://dx.doi.org/10.1021/jp407233k.
  29. A. Renaud; L. Cario; Y. Pellegrin; E. Blart; M. Boujtita; F. Odobel; S. Jobic, "The first dye-sensitized solar cell with p-type LaOCuS nanoparticles as a photocathode." RSC Adv., 2015, 5, 74, 60148-60151, http://dx.doi.org/10.1039/C5RA07859H.
  30. T. Jiang; M. Bujoli-Doeuff; Y. Farre; E. Blart; Y. Pellegrin; E. Gautron; M. Boujtita; L. Cario; F. Odobel; S. Jobic, "Copper borate as a photocathode in p-type dye-sensitized solar cells." RSC Adv., 2016, 6, 2, 1549-1553, http://dx.doi.org/10.1039/C5RA24397A.
  31. T. Jiang; M. Bujoli-Doeuff; Y. Farre; Y. Pellegrin; E. Gautron; M. Boujtita; L. Cario; S. Jobic; F. Odobel, "CuO nanomaterials for p-type dye-sensitized solar cells." RSC Adv., 2016, 6, 114, 112765-112770, http://dx.doi.org/10.1039/C6RA17879K.
  32. Y. Farré; M. Raissi; A. Fihey; Y. Pellegrin; E. Blart; D. Jacquemin; F. Odobel, "A Blue Diketopyrrolopyrrole Sensitizer with High Efficiency in Nickel-Oxide-based Dye-Sensitized Solar Cells." ChemSusChem, 2017, 10, 12, 2618-2625, http://dx.doi.org/10.1002/cssc.201700468.

PI: Fabrice Odobel

The possibility to use sunlight to activate cheap and stable raw materials such as water and CO2 to form hydrogen or carbon-based compounds to use subsequently as fuels or raw commodities for chemical industry is the basement of circular economy. Towards this objective, we aim at designing and synthesizing molecular scaffolds or hybrid systems made of molecules and semiconductors to mimic the function of the natural photosynthetic apparatus in order to successfully convert sunlight into chemical energy such as hydrogen or carbon monoxide (Figure 1).

Figure 1 : Natural versus artificial photosynthesis

More specifically, our works focus on two main axes: i) the development of molecular systems that reproduce the function of charge photo-accumulation and Z scheme, which represents a rather fundamental approach of artificial photosynthesis and ii) the fabrication of hybrid devices which practically produce solar fuels from water or carbon dioxide. These systems are composed of dye sensitized wide bandgap semi-conductors such as TiO2, NiO to develop dye sensitized photoelectrochemical cells (DSPECs) or the low bandgap semi-conductors used in photovoltaic such as amorphous silicon and copper indium gallium (di)selenide (abbreviated CIGS) coated with molecular catalysts to construct photoelectrochemical cells (PECs).

1. Molecular systems for charge photo-accumulation or Z Scheme function

1.1 Charge photo-accumulation

Most of the redox reactions involved in the activation of substrates into high energy content molecules (ex: 2 H+ + 2e- → H2 or CO2 + 6H+ + 6e- → CH3OH + H2O) are multi-electronic processes. This simple observation implies that it is mandatory to store, at least temporarily, several holes or electrons on one molecular entity, in order to achieve classical redox reactions through the use of photo-induced charge separation states.1 Nature has indeed developed an intricate molecular machinery in the course of evolution, allowing to store no less than four holes into a tetranuclear manganese cluster after four successive photon absorptions. This function which can be named charge photo-accumulation, is one of the irreplaceable actors of PSII, and yet has been the focus of very few studies, essentially centered on water oxidizing devices.

To realize charge photoaccumulation within simple molecular entities, one has to carefully choose the different constitutive units: the sensitizer S, and the hole and electron reservoirs. Polyoxometallates (POMs) are heteropolyanions which can accommodate several electrons at not very negative potentials, in a reversible manner. Moreover, they display electro-catalytic properties concerning protons reduction into H2 and water oxidation into oxygen. Flash photolysis of a solution of compound 14 in a mixture of DMF and water in presence of a sacrificial electron donor (triethanolamine: TEOA) yielded a doubly reduced POM, as evidenced by transient absorption spectroscopy (build-up of a broad structure-less absorption band between 650 and 1000 nm).2 This system behaves like a molecular capacitor, accumulating several electrons within its structure.

IMF - Photoaccumulative system

Figure 2. Photoaccumulative system based on the assembly of a POM and porphyrin dendronic antennas assembled by click chemistry

 

A hetero-supramolecular architecture was developed and allowed for the first time to store simultaneously two holes and two electrons on the same array.3, 4 This is the first step towards the conception of efficient photo-catalytic systems able to perform multi-electronic redox processes, such as water oxidation or reduction.

IMF - Hybrid system

Figure 3: Hybrid system capable of storing simultaneously two electrons and two holes on its structure.

 

1.2 Z Scheme function

Artificial photosynthesis requires to design a device, which can generate upon light excitation of both a strong oxidant to oxidize water and a strong reductant for proton or carbon dioxide reduction.  This is a very difficult endeavor because an excited state generated by a photon from visible light is usually not sufficiently high energy lying to promote both a strongly reducing and strongly oxidizing charge separated state. Accordingly, it is necessary to explore new concepts to solve the aforementioned problem.

Our solution is directly inspired from oxygenic photosynthetic system. Green plants take up this challenge thanks to the Z-scheme function which relies on the connection in series of two photosystems (PSI and PSII), both independently realizing the conversion of a photon into a charge separated state (Figure 4).5 In PSII, the absorption of a first photon promotes the oxidation of a special pair of chlorophyll (P680) and the reduction of a quinone (Q).

Another light absorption in photosystem I leads to the photo-oxidation of P700 and a reduced ferredoxin (FD). Conceptually, the energy produced in PSII is partly injected into PSI. As a result, a large difference of potentials can be reached between the final oxidant (P680+; E ≈ 1.4 V vs SCE) and the final reductant (FD-; E ≈ -1 V vs SCE) thanks to the build-up of a potential created by two photons absorbed in two different photosystems.

Another advantage of a Z-scheme approach compared to a single visible-light-responsive photosystem stems from the possibility to exploit a wider range of the solar spectrum, because the photonic energy required to build up the oxidant and the reductant in each photosystem can be reduced. This ingenious strategy is certainly the path towards efficient artificial photosynthetic systems.

IMF - Z Scheme function in green plants

Figure 4. Schematic illustration of the Z-scheme function in green plants. OEC = Oxygen Evolving Complex; Q = Quinone; Cyt = Cytochrome; Cyt f = Cytochrome b6f; PC = Plastocyanin; FD = Ferredoxin; FNR = Ferredoxin NADP Reductase.

 

Considering the unique advantage of the Z-scheme principle, we have embarked in the ambitious program aiming at constructing Z-scheme mimic driven by two-step photoexcitation in two different artificial photosystems.6, 7 For this purpose we have designed the Tetrad molecule “Bodipy-NDI-TAPD-Ru” (Figure 5), composed of two different dyes: the organic dye Bodipy and a RuII(bipyridine)3 derivative, which harvests light in a complementary manner between 400 and 600 nm.7 The naphthalene diimide (NDI) unit is a good electron acceptor while the tetraalkylphenyldiamine (TAPD) unit is a good electron donor.

IMF - Tetrad

Figure 5. Structure of the molecular Tetrad (up) and schematic energy diagram showing the pertinent states involves in the deactivation of the Tetrad via the Z-scheme principle (down).

In this Tetrad, light excitation of Bodipy and Ru complex units ultimately leads to two coupled photoinduced electron transfer events that produces a single charge separated state composed of an oxidized Bodipy+ and a reduced Ru(I) complex (Figure 5). The latter stores a larger energy content than individual photosystem does and provides thus the possibility to generate both a strong oxidant and a strong reductant with two photons of the visible spectrum.  The demonstration within a well characterized model establishes a link between fundamental studies of biological electron transfer and application for solar fuel production.

2. Hybrid devices for solar fules from DSPECs or PECs

The development of photocatalytic systems generating fuels with sunlight started by the end of seventies and there are many systems combining sensitizers and molecular catalysts and semiconductors that evolve hydrogen, or CO from CO2, upon visible light irradiation. However, despite these major advances, practical, cost effective technologies for large scale and environmentally friendly conversion of sunlight into solar fuels still remains a considerable of develop dye sensitized photoelectrochemical cells (DSPECs) and the utilization of low bandgap semi-conductors such as amorphous silicon and copper indium gallium (di)selenide (CuInxGa1-xSe2: abbreviated CIGS) that are abundantly used in the photovoltaic industry. The implementation of a cost-effective PV materials is very relevant to photocatalysis, because the wealth of photovoltaic manufacturing experience is already available for enabling its commercial large scale deployment.

First, our long standing expertise in the field of DSSC (see solar cell projects) enables us to implement the photoelectrodes for DSSCs toward the field of artificial photosynthesis for the development of DSPEC. In particularly, we have searched to exploit the photocathodes to drive the reduction of protons into hydrogen and carbon dioxide to carbon monoxide.8, 9, 10

IMF - p-DSPEC for protons reduction

Figure 6. Schematic representation of a p-DSPEC for protons reduction.

In this context, we have also developed a versatile click chemistry synthetic approach to post-functionalize the already anchored dye of any photoelectrode (either nanocrytalline TiO2 or NiO films) with a molecular component with minimum synthetic effort (Figure 7). More recently, we have demonstrated the great potential of CIGS for the development of photocatalytic systems for CO2 reduction with unmet efficiency and selectivity (Figure 7).11

IMF - click chemestry


Figure 7. Schematic principle of click chemistry on the electrodes and of a CIGS photocathode based on molecular catalyst grafted on a CIGS photocathode.

 

Collaborations :

 

Financements

  • MolecularZScheme (ANR blanc : 2013-2017);
  • NiOPhotoCat (PSR Région Pays de la Loire: 2012-2015);
  • LumoMOF (RFI Lumomat, Région Pays de la Loire: 2015-2018),
  • ClickHybridChem (RFI Lumomat, Région Pays de la Loire: 2017-2020), H
  • ybridZScheme (RFI Lumomat, Région Pays de la Loire: 2018-2019).

 

Références :

  1. Y. Pellegrin; F. Odobel, "Molecular devices featuring sequential photoinduced charge separations for the storage of multiple redox equivalents." Coord. Chem. Rev., 2011, 255, 21-22, 2578-2593, http://www.sciencedirect.com/science/article/pii/S0010854510002663.
  2. K. J. Elliott; A. Harriman; L. Le Pleux; Y. Pellegrin; E. Blart; C. R. Mayer; F. Odobel, "A Porphyrin-Polyoxometallate Bio-inspired Mimic for Artificial Photosynthesis." Phys. Chem. Chem. Phys., 2009, 11, 8767–8773, https://pubs.rsc.org/en/content/articlelanding/2009/CP/b905548g#!divAbstract.
  3. S. Karlsson; J. Boixel; Y. Pellegrin; E. Blart; H.-C. Becker; F. Odobel; L. Hammarstrom, "Accumulative electron transfer: Multiple charge separation in artificial photosynthesis." Faraday Discussions, 2012, 155, 0, 233-252, http://dx.doi.org/10.1039/C1FD00089F.
  4. S. Karlsson; J. Boixel; Y. Pellegrin; E. Blart; H.-C. Becker; F. Odobel; L. Hammarström, "Accumulative Charge Separation Inspired by Photosynthesis." J. Am. Chem. Soc., 2010, 132, 51, 17977-17979, https://pubs.acs.org/doi/10.1021/ja104809x.
  5. J. Barber, "Photosynthetic energy conversion: natural and artificial." Chem. Soc. Rev., 2009, 38, 1, 185-196, http://dx.doi.org/10.1039/B802262N.
  6. L. Favereau; A. Makhal; D. Provost; Y. Pellegrin; E. Blart; E. Goransson; L. Hammarstrom; F. Odobel, "Tris-bipyridine based dinuclear ruthenium(ii)-osmium(iii) complex dyads grafted onto TiO2 nanoparticles for mimicking the artificial photosynthetic Z-scheme." Phys. Chem. Chem. Phys., 2017, 19, 6, 4778-4786, http://dx.doi.org/10.1039/C6CP06679H.
  7. L. Favereau; A. Makhal; Y. Pellegrin; E. Blart; J. Petersson; E. Göransson; L. Hammarström; F. Odobel, "A Molecular Tetrad That Generates a High-Energy Charge-Separated State by Mimicking the Photosynthetic Z-Scheme." J. Am. Chem. Soc., 2016, 138, 11, 3752-3760, http://dx.doi.org/10.1021/jacs.5b12650.
  8. C. E. Castillo; M. Gennari; T. Stoll; J. Fortage; A. Deronzier; M. N. Collomb; M. Sandroni; F. Légalité; E. Blart; Y. Pellegrin; C. Delacote; M. Boujtita; F. Odobel; P. Rannou; S. Sadki, "Visible Light-Driven Electron Transfer from a Dye-Sensitized p-Type NiO Photocathode to a Molecular Catalyst in Solution: Toward NiO-Based Photoelectrochemical Devices for Solar Hydrogen Production." J. Phys. Chem. C, 2015, 119, 11, 5806-5818, http://dx.doi.org/10.1021/jp511469f.
  9. J. Warnan; J. Willkomm; Y. Farré; Y. Pellegrin; M. Boujtita; F. Odobel; E. Reisner, "Solar electricity and fuel production with perylene monoimide dye-sensitised TiO2 in water." Chem. Sci., 2019, 10, 9, 2758-2766, http://dx.doi.org/10.1039/C8SC05693E.
  10. C. E. Creissen; J. Warnan; D. Antón-García; Y. Farré; F. Odobel; E. Reisner, "Inverse Opal CuCrO2 Photocathodes for H2 Production Using Organic Dyes and a Molecular Ni Catalyst." ACS Catal., 2019, 9530-9538, https://doi.org/10.1021/acscatal.9b02984.
  11. P. Palas Baran; R. Wang; E. Boutin; S. Diring; S. Jobic; N. Barreau; F. Odobel; M. Robert, "Photocathode functionalized with a molecular cobalt catalyst for selective CO2 reduction in water." Nature Commun., 2020, accepted, n° ncomms-20-11404.

 

 

PI: Stéphane DIRING

Metal–organic frameworks (MOFs), also referred as porous coordination polymers are fascinating highly ordered structures, assembled from metal ions or clusters and organic ligands as building units that can in principle offer such degree of organization. Aside from conventional applications such as gas storage, separation, catalysis, etc., the modularity, nanoscale porosity, enormous chemical variety offered by these hybrid structures also makes them appealing platforms to design and study artificial photosynthetic systems.

Photo-induced processes in Metal-Organic Frameworks thin

Here, we aim at developing novel photoactive MOF thin films for solar energy conversion. Our approach is based on the controlled and hierarchical integration of multiple photoactive components within the same surface-grown MOF architecture. The main objectives of these new systems are to i) act as panchromatic light-harvesting antennas allowing for directional energy transfer, ii) achieve long-lived charge separated states, and iii) ultimately produce solar fuels, such as hydrogen, or reduce carbon dioxide, by combining these redox potentials with suitable electrocatalysts.

In-depth photophysical investigation will provide a better fundamental understanding of the energy and electron transfer dynamics at play within these hierarchical hybrid materials.

Schematic representation of multicomponent MOFs

Schematic representation of multicomponent MOFs

 

Collaborations 

  • Christoph Wöll, Ritesh Haladar, Ian Howard. Karlsruhe Institute of Technology (KIT)
  • Thoma Devic, Institut des Matériaux Jean Rouxel (IMN, Nantes)

 

Financements

  • LumoMOF (RFI Lumomat, Région Pays de la Loire: 2015-2018)
  • PhotoMOF (ANR-JCJC: 2018-2022)

 

Publications

  • A de novo strategy for predictive crystal engineering to tune excitonic coupling; R Haldar, A Mazel, M Krstić, Q Zhang, M Jakoby, IA Howard, BS Richards, N. Jung, D. Jacquemin, S. Diring, W. Wenzel, F. Odobel, C. Wöll ; Nat. Commun. 2019, 10, 2048. (link)
    de novo strategy for predictive crystal engineering
  • Crystalline chromophore assemblies render anisotropic energy transfer in metal-organic thin film ; Haldar, M. Jakoby, A. Mazel, Q. Zhang, A. Welle, T. Mohamed, P. Krolla, S. Diring, F. Odobel, B. S Richards, I. A. Howard, C. Wöll :Nat. Commun. 2018, 9, 4332. (link)
    IMF - Crystalline chromophore
  • Enhancing selectivity and kinetics in oxidative photocyclization by supramolecular control ; Haldar, S. Diring, P. K. Samanta, M. Muth, W. Clancy, A. Mazel, S. Schlabach, F. Kirschhöfer, G. Brenner Weiß, S. K. Pati, F. Odobel, C. Wöll ; Angew. Chem. Int. Ed. 2018, 57, 13662 –13665. (link)
    Enhancing selectivity and kinetics in oxidative photocyclization by supramolecular control
  • Excitonically coupled states in crystalline coordination networks ; Haldar, A. Mazel, R. Joseph, M. Adams, I. Howard, B. Richards, M. Tsotsalas, E. Redel, S. Diring, F. Odobel, C. Wöll ; Chem. Eur. J. 2017, 23, 14316. (link)
    Excitonically coupled states in crystalline coordination networks
  • Localized Conversion of Metal-Organic Frameworks into Polymer Gels via Light-Induced Click Chemistry ; Schmitt, S. Diring, P. G. Weidler, S. Heißler, S. Kitagawa, C. Wöll, S. Furukawa, M. Tsotsalas ; Chem. Mat. 2017, 29, 5982. (link)
    Localized Conversion of Metal-Organic Frameworks

 

PI: Yann PELLEGRIN

Photosensitizers (PS) naturally acquire enhanced reductive and oxidative power upon visible light irradiation: PS* is transiently generated and can either react with an acceptor A (oxidative quenching, OQ) or a donor D (reductive quenching, RQ) generating respectively PS+ and A- or PS- and D+. The corresponding chemical reactions are given below in figure 1:

IMF - Illustration of the oxidative and reductive quenching mechanisms

Figure 1. Illustration of the oxidative and reductive quenching mechanisms

 

The occurrence of OQ and RQ depends respectively on the photo-reductive and the photo-oxidative powers of PS*.  RQ produces PS- which is a more potent reductant than transient PS*. Thus RQ is preferable to reach high reductive power (for activation of reduction catalysts, or simple electron transfer to an acceptor having a deep LUMO. For instance, RQ took place between famous Ru(bpy)32+ and dithio anions1 as D affording Ru(bpy)2(bpy•-)+ featuring a potential of ca. -1.3 V, 500 mV more negative than the excited state oxidation potential of the couple Ru(bpy)33+/Ru(bpy)32+*.

Accordingly, the more cathodic E(PS/PS-), the stronger the reductive power which could be generated with PS* involved in a RQ process. Within this frame, PS chosen as homoleptic Cu(I) complexes CuL2+ (fig 2) (where L is a diimine ligand like 1,10-phenanthroline, bearing bulky substituents R in α of the chelating nitrogens) are very relevant and appealing alternatives to the heavy metal based dyes. Indeed, complexes of the general formula CuL2+ display very similar properties to Ru(bpy)32+ at lower cost and toxicity (MLCT transitions in the visible, the excited state is a charge transfer state, with a decent lifetime).

IMF - General structure of homoleptic copper(I) complexes

Figure 2. General structure of homoleptic copper(I) complexes

 

The relevant photophysical properties of copper(I)-diimine complexes originate in the steric bulk imposed by R (figure 2):2 upon photo-excitation, electron transfer from copper(I) ion to vicinal diimine entails the generation of formally copper(II) species, and therefore a distortion from tetrahedral to square planar geometry which opens several channels leading to a fast deactivation of the excited state.

Most importantly, Cu(I) complexes feature very negative reduction potentials, (e.g. -1.9 V/SCE for Cu(dipp)2+):3 RQ with such complexes, hereafter generically named PSCu, would yield massive reductive power, equal or superior to heavy metal based PS at lower cost. However, RQ with common CuL2+ is a difficult task because they are weak photo-oxidants, namely step 2 in figure 1 is thermodynamically uphill.4

With a view to implementing RQ with common CuL2+ complexes, we focused our attention on the Rehm and Weller equation which states that ΔGRQ (the driving force for RQ) is proportional to -(Ered + E00 – E(SD+/SD) where Ered is E(PSCu/PSCu-), E00 the energy of the excited state and E(SD+/SD) the redox potential associated to the sacrificial donor.

1. Design CuL2+ such that Ered is less cathodic.

Several complexes have been designed within this frame, by adding electron-withdrawing substituents on the phenanthroline ligand. In particular we prepared a series of complexes where the bulky groups R are plain halogen atoms (figure 3): the idea was to investigate whether halogens were sufficiently encumbering to promote the excited state properties of corresponding copper complexes, and observe the impact on the reduction potential Ered. We showed that the halogen atoms placed in positions 2 and 9 of phenanthroline had a very deep impact on the electronic properties of the resulting copper complexes.5

2. Design CuL2+ such that E00 is increased.

In order to increase E00 without altering the overall redox properties of the phenanthroline ligand, one can simply increase the steric bulk around the copper(I) ion. The stability of the coordination sphere is however at stake (the bulkier the ligands, the more fragile the complexes). In order to get stability and steric bulk, we prepared non symmetrical phenanthroline ligands bearing one ramified alkyl chain in one position, and a phenyl group in the other to implement stabilizing π-stacking interactions. This approach allows to improve by 150 meV the driving force for RQ.

3. Design SD such that E(SD+/SD) is less positive.

In order to qualify as a relevant sacrificial donor in the frame of RQ with copper complexes, the chosen reductant must be irreversibly oxidized at very low potential (ca. 0 V vs. SCE). In order to reach this goal, we focused on the chemical engineering of benzimidazoline derivatives (figure 3c), and modified the molecular skeleton with electron donating groups.

IMF - Examples of complexes illustrating the three different approaches we explored

Figure 3. Examples of complexes illustrating the three different approaches we explored.

 

Financials:

  • Project PERCO (ANR, 206-2021)

 

References:

  1. Cano-Yelo, H.; Deronzier, A. Net photoreduction of tris(2,2'-bipyridine) ruthenium(II) complex in acetonitrile. A photoelectrochemical cell application. Nouveau Journal de Chimie 1983, 7, 147-148.
  2. Armaroli, N.; Accorsi, G.; Cardinali, F.; Listorti, A. Photochemistry and photophysics of coordination compounds: copper. Top. Curr. Chem. 2007, 280, 69-115.
  3. Garakyaraghi, S.; Crapps, P. D.; McCusker, C. E.; Castellano, F. N. Cuprous Phenanthroline MLCT Chromophore Featuring Synthetically Tailored Photophysics. Inorg. Chem. 2016, 55, 10628-10636.
  4. Cunningham, K. L.; Hecker, C. R.; McMillin, D. R. Competitive energy-transfer and reductive quenching of the CT excited states of copper(l) phenanthrolines. Inorganica Chimica Acta 1996, 242, 143-147;  Cunningham, K. L.; McMillin, D. R. Reductive Quenching of Photoexcited Cu(dipp)2+ and Cu(tptap)2+ by Ferrocenes (dipp = 2,9-Diisopropyl-1,10-phenanthroline and tptap = 2,3,6,7-Tetraphenyl-1,4,5,8-tetraazaphenanthrene). Inorg. Chem. 1998, 37, 4114-4119.
  5. Brown-Xu, S.; Fumanal, M.; Gourlaouen, C.; Gimeno, L.; Quatela, A.; Thobie-Gautier, C.; Blart, E.; Planchat, A.; Riobé, F.; Monnereau, C.; Chen, L. X.; Daniel, C.; Pellegrin, Y. Intriguing Effects of Halogen Substitution on the Photophysical Properties of 2,9-(Bis)halo-Substituted Phenanthrolinecopper(I) Complexes. Inorg. Chem. 2019, 58, 7730-7745.

PI: Eléna ISHOW

Photochromic organic materials have been known for long for their ability to reversibly photoswitch under light stimulus. Ophthalmic lenses made out of them are the most representative accomplished example, offering unrivalled fast and high-quality eye protection from intense UV sunlight. They have thus stirred ceaseless interest in the field of data storage and optoelectronics to provide high-speed transfer, storage and treatments of optical data, or more recently in organic electronics to photomodulate the performances of the main devices.

In addition to their photoswitching properties, the class of azo photochromes display remarkable photomechanical properties, yielding fascinating mass transfer and deformation under structured illumination. To exploit such unique properties, we have been developing small molecule-based materials that can originally be processed as nanoparticles or associated to inorganic nanoparticles (gold, magnetic iron oxide) while keeping their photoactivity in the solid state. Our current interests focus on the creation of sub-micrometric patterns with modulated optical or magnetic properties, thereby serving as potential anti-counterfeiting marks.

We are also more recently harnessing such extensive photomechanical properties to elaborate multimodal nanoprobes, stimulating and boosting interests for health applications where the entry of photochromic compounds represents a buoyant field of investigations.

IMF - PHOTOSWITCHABLE NANOMATERIALS DATA-STORAGE

 

Collaborations :

  • Laboratory PPSM, ENS Paris Saclay – GDR CNRS Photo-electrostimulation
  • Jean-Luc Duvail et Bernard Humbert (IMN, Nantes) – Raman spectroscopy and magnetism
  • Nicolas Delpouve (GPM, Rouen) – Thermal analyses
  • Tony Maindron (CEA LETI, Grenoble) - OLED fabrication
  • Hiroshi Miyasaka (University of Osaka, Japan) –Femtosecond transient absorption spectroscopy
  • Albert M. Brouwer (University of Amsterdam, van’t Hoff Institute, Amsterdam, Netherlands) - Femtosecond transient absorption spectroscopy
  • François Lagugné-Labarthet (University of Western Ontario, London, Canada) – Raman and vibrational spectroscopies
  • Cleber R. Mendonça (University of São Carlos, São Carlos, Brasil) – Nonlinear optical measurements

References:

  1. J. Phys. Chem. C 121 (29), 15908–15914, 2017 (link)
    Teulle, A. Sancho, E. Ishow, J. Sharma, A. Arbouet, C. Girard, E. Dujardin*
    Photochemical imaging of plasmons in multimodal 2D colloidal gold cavities
  1. ChemPhotoChem 1, 6-11, 2017 (link)
    Girard, J. Hémez, V. Silvestre, C. Labrugère, L. Lartigue, J.-L. Duvail, E. Ishow*
    Strong color tuning of self-assembled azo-derived phosphonic acids upon hydrogen-bonding.
  1. Org. Electron. 49, 24-32, 2017 (link)
    Olivier, E. Ishow, S. Meunier Della-Gatta, T. Maindron*
    Optimization study of inkjet deposition of a hole-transporting small molecule to realize a green top-emitting OLED together with an ald-made thin-film encapsulation.
  1. ACS Appl. Mater. Interfaces 8 (25), 16207-16217, 2016 (link)
    Derue, S. Olivier, D. Tondelier, T. Maindron, B. Geffroy*, E. Ishow*
    All-solution-processed organic light-emitting diodes based on photostable photocrosslinkable fluorescent small molecules.
  1. ACS Appl. Mater. Interfaces, 7 (3), 1932-1942, 2015 (link)
    E. Snell, J.-Y. Mevellec, B. Humbert, F. Lagugné-Labarthet, E. Ishow*
    Photochromic organic nanoparticles as innovative platforms for plasmonic nanoassemblies.

 

Funding:

  • DGA Tech: Contrat thèse – NAP2 (2018-2022)

PI: Clémence QUEFFÉLEC

Present members: Gennaro PICARDI, François-Xavier LEFÈVRE, Bruno BUJOLI, Clémence QUEFFÉLEC

IMF - Plasmonic nanomaterial

Metallic nanoparticles (NPs) have many useful properties, in particular some NPs have unique optical qualities while interacting with light known as surface plasmon resonance (SPR). Plasmon excitation leads to a range of effects on molecule adsorbed or bound or in proximity to a NP such as thermal effects or charge transfer.

Our main focus is to use the SPR phenomenon for accelerating catalytic reaction rates under laser irradiation using a well-designed molecular catalyst bound to metallic NPs and understand which types of mechanism are occuring.

We have already investigated the Ullmann reaction under laser irradiation. This is a classical example of catalytic carbon-carbon bond forming process, based on the coupling of aryl halides mediated by copper. The hybrid nanocomposites we synthesized were proven to be efficient in accelerating the rate of the latter reaction under light irradiation.

We focused our investigation as well on catalytic hydrolysis of methyl parathion (MeP). MeP is a compound used in large-scale as pesticide and insecticide, but is a nerve agent obviously dangerous to the health.

We are currently investigating other copper-catalyzed challenging reactions with different types of molecular catalysts bound to different type of metallic NPs.

 

Collaborations :

  • B. Humbert and JY Mevellec (IMN, Nantes University, France),
  • M. Lamy de la Chapelle (IMMM, Le Mans University, France),
  • Nordin Felidj (Itodys, Paris University, France),
  • Claire Mangeney (LCBPT, Paris University, France),
  • D.A. Knight (Florida Institute of Technology, Florida, USA).

 

Financements :

  • Région Pays de la Loire (Pari Scientifique X-TREM),
  • CNRS (Projet PICS COSMOCAT).

 

References:

  • Forato F.; Talebzadeh, S.; Bujoli, B.; Queffélec, C.; Trammell, S.A.; Knight, D.A. “Core-shell Ag@TiO2 nanocomposites for low-power blue laser enhanced copper(I) catalyzed Ullmann coupling” ChemistrySelect 2017, 2, 1-6.
  • Talebzadeh, S.; Forato F.; Bujoli, B.; Trammell, S.A.; Grolleau, S.; Pal, H.; Queffélec, C.;  Knight, D.A “Non-photochemical catalytic hydrolysis of methyl parathion using core-shell Ag@TiO2 nanoparticles” RSC Adv. 2018, 8, 42346-42352.
  • Forato F.; Talebzadeh S.; Rousseau N.; Mevellec J.Y.; Bujoli B.; Knight D.A.; Queffélec C.; Humbert B. “Functionalized core–shell Ag@TiO2 nanoparticles for enhanced Raman spectroscopy : a sensitive detection method for Cu(II) ions” Phys. Chem. Chem. Phys. 2019, 21, 3066-3072.
  • Talebzadeh S.; Queffélec C.; Knight D.A. “Surface Modification of Plasmonic Noble Metal – Metal Oxide Core-Shell Nanoparticles” Nanoscale adv. 2019, 1, 4578-4591
  • Queffélec, C.; Forato F.; Bujoli, B.; Knight, D.A.; Fonda, E.; Humbert, B. “Investigation of copper oxidation states in plasmonic nanomaterials by XAS and Raman spectroscopy” Phys. Chem. Chem. Phys. 2020, 22, 2193-2199.
  • Gennaro P., Humbert B., Lamy de la Chapelle M., Queffelec C. “Surface Modification of Au Nanoparticles with Heteroleptic Cu(I) Diimine Complexes” J. Phys. Chem. C 2020.